To evaluate the yield of different productive areas (determine the influx profile) based on the energy conservation law for mixing streams, a high accuracy of the borehole fluid temperature measurement is required and the temperature of the influx (fluid flowing into the borehole from the productive formation) needs to be known. Until now, the influx temperature has been calculated as the sum of the formation rocks temperature and thermodynamic value of Joule-Thomson effect. In general, the accuracy of the influx temperature evaluation is in the order of 1 K which is not sufficient to quantify the influx profile, therefore, thermometry is only used to ensure a reliable influx profile evaluation. More accurate results are supposed to be obtained from complex temperature data, namely, the data which, alongside with the influx temperature obtained through standard temperature logging, also includes temperature measurement of the fluid flowing into the borehole from productive strata.
On the other hand, from the prior art it is known (Chekalyuk E. V. Thermodynamics of Oil-Bearing Layer, Nedra, 1965, p. 238) that the temperature of the fluid flowing into the borehole, even from the initially isothermic formation changes over the time (in engineering literature this effect is referred to as non-stationary Joule-Thomson effect). The information of the influx temperature change rate as function of time may be used to determine the parameters of the polluted reduced-permeability near-borehole area (Yu. A. Popov, V. P. Pimenov, V. V. Tertychnyi, Developments of Geothermal Investigations of Oil and Gas Fields, Oilfield review, spring 2001, pp. 4-11).
Therefore, the claimed apparatus for the borehole influx fluid parameters measurement, particularly influx temperature, enables high-accuracy determination of both temperature and other parameters of the fluid flowing into the borehole from the productive formation.
In terms of engineering essence, the closest apparatus for the borehole influx fluid parameters measurement is the apparatus for the measurement of temperature, phase composition and flow rate of the fluid flowing into the borehole or injected into the formation as disclosed in U.S. Pat. No. 5,551,287. The main element of the apparatus as disclosed in the patent above is a fragment of a thin-wall cylinder with the curvature radius equal to the inner radius of the cased borehole. The cavity in the central part of this apparatus includes numerous thin plates positioned perpendicularly to the cased borehole surface. During the implementation of the method of the influx fluid temperature measurement using this apparatus the apparatus is located in the influx zone on the borehole inner wall and pressed thereto. Therefore, the fluid from the perforation channels can freely flow between the said plates into the borehole central part. The apparatus provides fluid stream isolation from the borehole fluid stream. The fluid temperature is measured with the transducers positioned in these plates.
The disadvantage of this engineering solution is low accuracy of the measured fluid temperature values because the facilities used in the apparatus do not duly prevent mass- and heat-transfer between the formation and borehole fluid which influences the accuracy of the obtained measurement data of the fluid parameters and the data obtained do not reflect their true values.